Question

When heated in air, coal burns and produces mainly:
(A)- Ozone gas
(B)- Hydrogen gas
(C)- Carbon monoxide gas
(D)- Carbon dioxide gas

Answer 1

Hint Coal mainly reacts with the oxygen present in air. The carbon present in coal gets oxidised to give a gas as a product. This gas is the prime factor for increase in global warming. The solid state of the gas is called dry ice because it does not wet the container or fabric. The gas is also an example of greenhouse gas.

Complete answer:
Coal is a combustible blackish brown sedimentary rock, formed from coal seams in the form of rock strata. Coal consists of carbon to a major extent along with other elements like hydrogen, sulphur, oxygen and nitrogen.
Coal is formed when dead plant matter decays to form peat. Peat is then converted to coal by heat and pressure as it is buried deep down the earth's surface. Coal is mainly used as a fuel that provides energy. The usage of coal increased after the industrial revolution. Even today coal is used as a fuel although other renewable sources of energy have been discovered as coal is extremely abundant in nature.
The combustion of coal gives energy along with a gas called carbon dioxide. Carbon dioxide emissions is a major cause for rising temperature as it is a greenhouse gas. Carbon dioxide traps the heat from going outside the atmosphere.

Therefore, the correct answer is option (D).

Note: Along with coal, complete combustion of hydrocarbons gives carbon dioxide as a product. However, incomplete combustion of hydrocarbon or coal gives carbon monoxide as a product. Carbon dioxide interferes with the respiration of the human body as the affinity of haemoglobin towards carbon monoxide is much more than that of oxygen.